Rucola is a traditional salad vegetable originating from the Mediterranean area, which has in recent years also become very popular with consumers in the USA and the EU. Rucola is grown and sold as leaves and is also called rocket, roquette, arugula and others. Rucola includes Eruca sativa and a number of species of the genus Diplotaxis. E. sativa (“cultivated rucola”) is faster growing and more cold tolerant than Diplotaxis species (“wild rucola”) and its taste is milder and therefore preferable in some market segments, whereas Diplotaxis species with their stronger taste and longer shelf life are preferable in other market segments. E. sativa and Diplotaxis are both a member of the Cruciferae family.
Plant breeders have worked to improve the genetic composition of E. sativa plants with a view to creating varieties that are superior to known varieties. Examples of desired improvements are plants having increased yields, disease resistance, shelf life, taste, stress tolerance or earliness.
One approach to achieve this goal in vegetable crops has involved crossing desirable genetic traits into plants and then developing them into pure breeding lines by successive generations of self pollination. Superior lines are then combined to form a uniform F1 hybrid that contains the desirable genetic traits and eliminates inbreeding depression. In the vegetable seed markets all major vegetable crops, except lettuce, are today dominated by such superior F1 hybrids due to their clear advantages over non-hybrids.
There is however no cost effective hybridization system available for rucola. This greatly restricts the potential to improve rucola, in particular E. sativa plants. There is therefore an unmet need for developments allowing the routine and cost-effective production of hybrids in rucola, in particular in E. sativa. 